This invention relates to turbine pumps. A turbine pump is a type of rotary pump having blades at the outer periphery of the impeller to move fluid through an annular pumping chamber within a casing from an inlet to an outlet as the impeller rotates. A dam is provided in the casing to direct pumped fluid to the outlet.
Turbine pumps have a number of uses, including fabric washing machines for example. In such machines the pump acts to remove water from the tub and discharge it to a drain. Often the pump also acts to recirculate water from the tub through a filter and back to the tub. Turbine pumps are particularly adapted for use in fabric washing machines because the impeller may be spaced relatively far from the peripheral wall of the pump chamber. This enables the pump to pass lint and small objects, such as buttons for example, which become entrained in the water.
Typically in clothes washers, it is desired to provide a higher rate of fluid flow during drain than during recirculation. One approach to obtain such an operation is illustrated in U.S. Pat. Nos. 3,127,839 and 3,127,840, both of which are assigned to General Electric Company. Those pumps have reversible impellers and use separate halves of the pumping chamber to pump fluid, depending on the direction of impeller rotation. While effective, this approach does not make most efficient use of the pump in either direction.
Some such pumps are "double decked;" that is, they effectively have two impellers in separate chambers. A different impeller is utilized for each direction of impeller rotation. Such constructions are rather complicated, which adds to the cost of manufacture.
It is an object of the present invention to provide a reversible turbine pump.
It is another object of this invention to provide such a reversible turbine pump which makes optimum use of the pumping cavity.
It is a further object of this invention to provide such a pump which can be accurately assembled in a low cost manner in an automated assembly operation.